The rational design of prosthetic heart valves requires a theoretical technique for the prediction of the flow pattern of blood in the heart and the analysis of the interaction of that flow pattern with the motions of the valves and heart muscle. We have developed a contractile computer test chamber for mitral valves, the parameters of which have been adjusted so that the test conditions are physiological. We plan to use this test chamber for detailed computer studies of a variety of prosthetic valves. In these studies the prosthetic values will be compared with each other and with a natural valve standard. In addition, we plan to elucidate the fluid dynamics of the natural mitral valve by studying the role of the contractile mitral ring, the effect of diastolic tension on the chordae tendinae, and the contribution of atrial systole to ventricular filling and valve closure. Computational methods for the heart valve problem in three dimensions will also be developed.